Heparin-Released Plasma Lipase Activities, Lipoprotein and Apoprotein Levels in Young Adult Cyclists and Sedentary Men

Serum lipid and lipoprotein levels, apolipoproteins A-I and B, and lipolytic enzyme activities were studied in 14 young male cyclists and in 21 age-matched sedentary controls. While there were no significant differences in serum cholesterol between the two groups, the cyclists showed a significant decrease in serum triglycerides (P less than 0.05) and LDL cholesterol (P less than 0.05) and had significantly higher levels of HDL cholesterol (P less than 0.01) and HDL2 cholesterol (P less than 0.001). Significantly lower serum cholesterol/HDL cholesterol (P less than 0.001) and LDL cholesterol/HDL cholesterol (P less than 0.001) ratios and a significantly higher HDL2 cholesterol/HDL3 cholesterol ratio (P less than 0.001) were observed in the athletes. Serum apolipoprotein B was lower and the Apo B/Apo A-I ratio significantly reduced in the athletes. No significant differences emerged between the two groups in plasma post-heparin lipoprotein lipase activity (LPL) and in hepatic triglyceride lipase activity (HTGL), and there were no correlations between HDL cholesterol and lipolytic enzyme activities. In conclusion, this cross-sectional study may indicate that an aerobic training program such as cycling is associated with an advantageous lipoprotein pattern; some factors other than lipolytic activity may contribute to increase the HDL cholesterol levels in physical training.